1. Field of the Invention
The present invention relates to a display device having a plurality of light emitting elements arrayed in a matrix form on a display panel, the luminance of each light emitting element being controlled by a current value, and more particularly to a temperature control method for a display device and a display device capable of controlling the temperature of a display panel with a simple configuration.
2. Description of Related Art
In a display device having a large number of light emitting elements arrayed in a matrix form on a display panel, with the luminance of each light emitting element being controlled by a current value, it is generally required to increase a value of current to be supplied to each light emitting element in order to obtain a high luminance. However, as the current value is increased, the light emitting element generates heat, shortening the lifetime of the element.
An emission efficiency of a light emitting element has improved in recent years, and a signal level in an ordinary image display state is reduced by more than half of the signal level presenting a maximum luminance. The lifetime of a light emitting element is therefore rarely shortened by heat generation. However, for example, in the worst state in which a full white display state continues for a long time, a light emitting element may generate heat and be damaged.
In order to settle this issue, there has been proposed a display device in which an operational environment temperature of a display panel is detected, and when this temperature exceeds a predetermined temperature (e.g., 50° C.), the drive voltage value of a light emitting element is changed and each light emitting element is driven to make the luminance value of the light emitting element lower than a predetermined luminance value (e.g., refer to Japanese Unexamined Patent Application Publication No. 2005-31430(hereinafter referred to as “Patent Document 1”)).
In another display device, a temperature detector is provided to each of a plurality of organic electro luminescence elements (hereinafter called “organic EL element”) serving as light emitting elements and arrayed in a matrix form, and emission control of each organic EL element is performed by using temperature data detected with each temperature detector (e.g., refer to Japanese Unexamined Patent Application Publication No. 2002-175046(hereinafter referred to as “Patent Document 2”)).